Next-generation electronic overload relay from Rockwell

Although the E300 is referred to as an overload relay it actually performs many protection functions:

• Under and over current
• Under and over voltage
• Stall
• Jam
• Phase loss
• Ground fault
• Thermistor

Bill Martin, global product manager at Rockwell Automation, says: "As adoption of electronic-overload-relay technology has risen over the past decade, so have practical expectations. Customers told us they value the technology's remote monitoring and predictive trip alerts, but they also want designs that simplify programming, preserve network nodes, save wiring time, ease maintenance and minimise catalogue numbers."

The E300 overload relay's native dual-port EtherNet/IP option simplifies network wiring by enabling E300 relays to be daisy-chained and by eliminating the need for an Ethernet switch. The E300 overload relay also features an embedded web server so maintenance personnel can use any web browser to integrate the E300 overload relay from any Internet-enabled device without the need for special software. To maintain uptime in the event of a network node interruption, the E300 supports a device-level ring (DLR) network topology.

A further way in which the E300 helps to maximise uptime is the extensive diagnostics capabilities:

• Current, voltage and power
• CIP Energy capable
• Trip and warning logs
• Per cent thermal capacity utilisation
• Time to trip
• Time to reset
• Operational hours
• Number of starts
• Phase rotation
• Frequency

Rockwell's E300 easily integrates into the Rockwell Software Studio 5000 control environment via an add-on profile. This integration brings users five mouse clicks away from communicating data between the device and a Logix controller.

Each E300 contains an embedded Allen-Bradley DeviceLogix logic engine with preprogrammed motor-control logic for local and remote motor operation, thereby simplifying integration within automation systems. For example, the E300 can be programmed to perform logic functions, run timers and control PID loops. One cable connects the E300 to the operator station for local motor operation, thereby eliminating the traditional hard-wiring time and costs, and consumption of discrete input points on the device. To ease swapping of E300 overload relays, the operator stations also support a copycat feature that enables users to download pre-stored relay configurations at the push of a button.

For those interested in energy consumption, the E300 is CIP Energy capable and can, within reason, be used as an energy monitor.

Expansion I/O reduces wiring time and network node count

The E300 overload relay offers a variety of digital and analogue expansion I/O modules, enabling users to maximise the relay's capability, all within a single network node. The E300 digital expansion I/O modules provide four inputs and two relay outputs, making it suitable for complex starter scenarios where users require more inputs and outputs than provided in the base overload. In addition, the relay's analogue expansion I/O modules enable users to select between traditional analogue signals and a range of specific resistance temperature detectors (RTDs) embedded in the motor. Combining the ability to receive both traditional analogue signals and RTD sensor signals in one device is claimed to be an industry first.

Rockwell's E300 overload relay contains a patented current-sensing system that leverages Rogowski technology. According to the company, this enables the E300 overload relay to remain the most compact architecture-class overload relay on the market, while still offering a wide 10:1 FLA range. This wide FLA range translates to fewer SKUs, which simplifies selection and reduces inventory.

Modularity provides users with the flexibility to tailor the relay to meet their sensing, control and communication needs. The sensing module is available with a combination of current, voltage and ground-fault-sensing capabilities, as well as direct contactor mount, panel-mount and pass-through styles. The control module is available with variations of AC and DC digital inputs, as well as positive temperature coefficient (PTC) and ground-fault options. In addition, a variety of communication modules enable the E300 overload relay to be used on EtherNet/IP and DeviceNet networks, and in standalone applications. Optional accessories include control stations, both with and without displays.

Although the E300 is more expensive to purchase than a standard overload relay, the potential savings in downtime could easily justify the additional outlay for applications beyond those where motors have been traditionally considered to be critical.

Follow the link for more information about the Allen-Bradley E300 electronic overload relay.